Proofing of a color printout before printing a large number of copies of the color printout is well-known in the art and is a time-consuming process. The proofing process is illustrated in FIG. 3 and typically includes the scanning of a color original, via a color separation scanner 10 to produce a plurality of color separation signals, typically in the Cyan-Magenta-Yellow-Black (CMYK) color coordinate system.
An exposing unit 12 then utilizes the color separation signals to produce a plurality of films 14, one for each color separation signal.
The films 14 are typically utilized by a printing press 16 for producing a multiplicity of color prints 18. However, because the number of prints 18 produced is very large, a test print, known as a proof 20, is first prepared and used to check that the prints 18 will be as desired. It is generally required that the proof 20 be as close to the print 18 as possible, where closeness is measured in the position of the elements on the page and in the color match between the proof 20 and the prints 18.
There are several parameters that are checked on proof 20. One is the placement of the image on the page, another is the accuracy of the color. If the color accuracy does not match that desired by the customer, then something in the process must be modified. The films 14 can be modified, by a process called dot etching, or new films 14 can be produced by rescanning the color original after at least some of the scanning parameters of the scanner 10 have been changed.
The proof 20 is typically produced in a conventional photomechanical process 22, which mimics the printing process. Examples of a mechanical process 22 are the CROMALIN process of DuPont or the MATCHPRINT process of 3M, both of the USA. If the proof 20 is not desirable for whatever reason, the proofing cycle, the cycle of scanning the original and evaluating the proof, is repeated until an acceptable proof 20 is achieved. This method is time-consuming and can take up to a few days.
Another proofing method is called a press proof. In this method, printing plates are produced from the films 14 and are used to produce proofs by simulating the press run.
A further proofing method, shown with dotted lines, includes the use of a Direct Digital Color Proofer (DDCP) in conjunction with a Color Electronic Prepress System (CEPS) 26. The CEPS receives the color separation signals, allows an operator to manipulate the signals as desired, and then provides the manipulated signals to both the exposing unit 12 and the DDCP 24. An example CEPS is the RESPONSE System manufactured by Scitex Corporation Ltd. of Herzlia, Israel. Example DDCPs are the Approval System manufactured by Eastman Kodak Company of Rochester, N.Y., U.S.A. or the Smartjet 3024 or 4012 proofers manufactured by Iris Graphics Inc. of Bedford, Mass., U.S.A.
The DDCP 24 is controlled by the CEPS 26 and is operative to produce proof 20. If the proof 20 is not desirable, for whatever reason, then either the original is rescanned as described hereinabove, or the operator uses the CEPS 26 to modify the signals as desired.
When the proof 20 is acceptable, the CEPS 26 provides the modified signals to the exposing unit 12 for exposing of films 14 for use in the press run.
The DDCP 24 typically has a different color coordinate system from the printing press 26. Therefore, modification of the color separation signals is necessary to ensure that proof 20 closely resembles the prints 18. U.S. patent application Ser. No. 07/650,468 filed Feb. 4, 1991, now U.S. Pat. No. 5,098,241 to the applicant describe such color modification methods.
Using the DDCP 24 reduces the length of the proof cycle. However, the DDCP 24 works only in conjunction with the CEPS 26. A stand-alone scanner 10 cannot be connected directly to a DDCP and therefore, must produce a proof 20 by first producing films 14.